Laser driven ion accelerator

ABSTRACT

A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

RELATED APPLICATION

[0001] This application related to U.S. Provisional No. 60/224,386 filedAug. 9, 2000, and claims priority thereof.

[0002] The United States Government has rights in this inventionpursuant to Contract No. W-7405-ENG-48 between the United StatesDepartment of Energy and the University of California for the operationof Lawrence Livermore National Laboratory.

FIELD OF THE INVENTION

[0003] This invention relates to method and apparatus for acceleratingparticles and, more particularly, to a method and apparatus ofaccelerating particles to achieve optimal energies.

BACKGROUND OF THE INVENTION

[0004] Conventional radiation therapy utilizes electron beams and x-raysas a means of treating and controlling cancer. Due to the inability ofcurrent technology to preferentially deposit the radiation at the siteof the cancer, healthy tissues between the tissue surface and the canceralso receive high doses or radiation and, therefore, are damaged.Consequently, physicians use a less-than-optimal dose to reduce theundesirable damage to healthy tissues and the subsequent side effects.In many cases, this proves to be an unacceptable alternative.

SUMMARY OF THE INVENTION

[0005] Aspects of the present invention include an accelerator systemhaving a light source; and a target having a concave shape.

[0006] Aspects of the present invention further include a methodincluding firing a laser pulse having an energy range of approximately 1to approximately 10 Joules from a light source at a target; guidingradiation elements emitted from said laser pulse striking said target;discriminating ions having a predetermined energy range from saidradiation elements; and delivering said ions in an energy range ofapproximately 10 to approximately 500 Mega-Electron Volt (MeV) to atreatment field.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The accompanying drawings, which are incorporated into and form apart of the disclosure,

[0008] FIGS. 1A-1C illustrate a schematic diagram of a first embodimentof an accelerator system;

[0009]FIG. 2 is a side view of a target used in the accelerator systemof FIGS. 1A-1C;

[0010] FIGS. 3A-3E are alternative target configurations that may beused in the accelerator of FIGS. 1A-1C;

[0011] FIGS. 4A-4E are alternative target surfaces that may be used inthe accelerator system of FIGS. 1A-1C;

[0012]FIG. 5 is a schematic view of a prepulse control structure thatmay be used in the accelerator of FIGS. 1A-1C;

[0013]FIG. 6 is a schematic diagram of a second embodiment of theaccelerator system; and

[0014]FIG. 7 is a side view of an alternative configuration of a filmused in the accelerator system of FIG. 6.

DETAILED DESCRIPTION OF THE INVENTION

[0015] Disclosed herein are described accelerator systems and methodswhich may deliver protons and other ions to higher energies in anefficient manner. The accelerator systems and methods described hereinmay be in a compact or portable form to increase the flexibility of itsuse. Exemplary applications of the disclosed accelerator systems andmethods may include radiation oncology; ion radiology; ion isotopesources; pion, muon, and neutrino beams sources; and spectroscopicdiagnosis (nondestructive or otherwise) of different types of materials.For illustrative purposes, the exemplary embodiments disclosed hereinmay be used in radiation oncology applications.

[0016] FIGS. 1A-1E illustrate a schematic view of an embodiment of anaccelerating system 100. The accelerating system includes the followingcomponents: a light source system (e.g., laser system) 101 producing anenergy pulse 102 which travels through a light source guide system 101 bto a target system 110 located in a vacuum chamber 108. The pulse 102strikes the target 200 in the target system 110 and an ion beam 102 a isproduced which travels through an ion beam transport system andirradiation system 120 to a treatment field 150. The operation of theaccelerating system 100 is controlled by a controller 160 and feedbacksystem 170. These components may combine to form a compact (e.g.,portable, tabletop) accelerating system. The length, L1, of the lightsource system 101 and light source guide system 101 b may be in therange of approximately 1 to approximately 2 meters. The length, L2, ofthe target system 110 and a first section 120 a of the ion beamtransport and irradiation system 120 may be in the range ofapproximately 1 to approximately 2 meters. Therefore, the overall lengthof the light source system 101, light source guide system 101 b, thetarget system 110 and a first section 120 a of the ion beam transportand irradiation system 120, L3, may be in the range of approximately 2to approximately 4 meters. The length, L4, of separation of the vacuumchamber 108 and the treatment field (or object) 150 may vary dependingon the specific application. For example, L4 may range fromapproximately 0.25 to approximately 10 meters. It is to be understoodthat these exemplary lengths may vary higher or lower, again, dependingon the specific application.

[0017] The accelerating system 100 is controlled by a controller 160whose functions will be described in detail below. In order to maximizea flux of ions produced in the accelerator system 100, a chirped-pulseamplification (CPA) based, compact, high-repetition, high fluence lasersystem (e.g., a Ti: sapphire laser) may be utilized as a light sourcesystem 101. The basic configuration of such a light source system 101 isdescribed in U.S. Pat. No. 5,235,606, issued Aug. 10, 1993 to Mourou etal., which is hereby incorporated by reference. The light source system101 having a pulse shaper 101 a emits an energy pulse (or pulses) 102having a pulse energy of approximately 1 to approximately 10 Joules (J).The pulses 102 may be delivered at a rate of approximately 0.1 toapproximately 100 Hertz (Hz). The pulses 102 are transported by a lightsource guide system 101 b which may include a series of mirrors 104 andthin foils 105. Mirrors 104 are configured to guide and focus the pulse102 with a predetermined intensity using the last mirror in the mirrorseries 104. Before the pulse 102 enters the target system 110, the lightsource guide system 101 b may include a series of thin foils (e.g.,metal) 105 that are capable of controlling or reducing the prepulse ofeach pulse 102. The prepulse section of each pulse 102 may comprise afield of the pulse 102 prior to the arrival of the main peak of thepulse 102. Because a pulse 102 may be very short and intense, even afraction of the peak intensity of the pulse 102 (e.g., the prepulse) maybe sufficient to ionize and/or ablate the foils 105. The prepulse may becontrolled by using multiple foils 105 and a pulse shaper 101 a in thelight source system 101. The pulse shaper 101 a may optionally include afrequency multiplier.

[0018] Controller 160 and feedback system 170 are configured to performmonitoring, controlling and feedback functions for the acceleratorsystem 100. Controller 160 may be a microprocessor or other conventionalcircuitry. A plurality of sensors 103 monitor the intensity of the pulse102 and ion beam 102 a throughout the accelerator system 100. Asillustrated by FIGS. 1B and 1C, monitoring points where sensors 103 arepositioned may include the light source system 101 output, mirror series104 output, the target entry point of the pulse 102, after the target200, before slit 122, before magnets 123, after filters 126, and beforeand after the treatment field 150. In alternative embodiments, it is tobe understood that sensors 103 may not be limited to these numbers orpositions. The monitoring information is forwarded through the feedbacksystem 170 to the controller 160. Based on this input, controller 160 isconfigured to fine-tune the light source system 101 and may providecontrol signals to light source 101, mirror series 104, foils 105,magnets 123, 125, 129 and filters 126 to adaptively control the qualityof pulse 102 and ion beam 102 a. Parameters of the pulse 102 and ionbeam 102 a which may be adaptively controlled by the controller 160 andthe feedback system 170 may include repetition rate, laser flux, focus,aperture, angle, intensity, and pulse length.

[0019] The pulses 102 may be guided by the a light source guide system101 b into vacuum chamber 108 which encloses target system 110. Thetarget system 110 may be composed of prefoils, target feed, slits andshields represented by reference numeral 107 and a target 200. (Target200 may also be referred to herein as a foil, a film, a source andaccelerator element, or an interaction element). Pulses 102 may beintense, ultrafast (i.e., having a pulse length between approximately 1to 500 femtoseconds (fs)) and ultra-relativistic. During operation, thepulses 102 immediately (within a few fs of the pulse entry to the target200) and substantially destroy the target 200 and ionize multipleelectrons per each of the atoms contained in the target 200 to form“hot” electrons. Hot electrons may be defined as electrons having energygreater than approximately 1 MeV. Together with conduction bandelectrons, these hot electrons form a high density electron cloud 201 bin region 201 that is driven forward by the acceleration and heating ofthese electrons to high energies by the light source system 101. Anelectrostatic field is set up through charge separation by these hotelectrons. Therefore, according to a simple one-dimensional model, anaccelerating gradient E₀ is wavelength, λ, proportional to the energy(or temperature) of hot electrons divided by the width of the chargeseparation, which is approximately the Debye length λ_(D) of hotelectrons:

E ₀ =αT _(h)/λ_(D),

[0020] where α is a constant (about 5 to 10) and T_(h) is the energy ofhot electrons. The energy gain of ions may be the following:

E_(I) ql E ₀,

[0021] where q is the ion charge and l is the acceleration distance.Therefore,

E _(I) =αq(l/λ _(D))T _(h.)

[0022] When l is approximately λ_(D), which is the case for a simpleone-dimensional geometry, an energy gain of ions is obtained as

E _(I) ≡ql E ₀.

[0023] Based on these equations, the acceleration system 100 is designedto enhance E_(I) by increasing a, l/λ_(D), and T_(h) (and except forprotons, q also).

[0024] For example, when the geometry of the target 200 has asubstantially concave geometry as shown in FIG. 2, both α and l may beincreased. If electrons are heated or accelerated to higher energy,T_(h) (or even T_(h)/λ_(D)) increases. This is because λ_(D) isproportional only T_(h) ^(½). The changing target parameters (which arediscussed in detail below) may increase α, l , or T_(h), or all ofthese.

[0025] During operation, the energy of the light source system 101 maybe compressed into an ultrashort time scale of approximately 10 to 100fs after a CPA's time stretcher and compressor (not shown), but beforethe final focal mirror in the mirror series 104. The final focal mirrorin the mirror series 104 may focus the pulse 102 which has beentime-compressed into a spatially compressed light spot (H in FIG. 2) onthe target 200 in the target system 110. The distance, d1 (as shown inFIG. 1A), from the final focal mirror in the mirror series 104 to thetarget 200 may be substantially less than 1 meter (m). The light sourcesystem 101 is capable of delivering to the target 200 a light beamintensity in the range of approximately 10¹⁸ to 10²³ Watts(W)/centimeter (cm)², with approximately 10²¹ W/cm² being the typicalintensity. The target system 110 is designed to allow the opticalinteraction of the intense short pulse 102 with the target 200 to yielda high flux of energetic ions such as protons 201 a (as shown in FIG.1B). As discussed above, the target 200 may be substantially destroyedwhen struck by the pulse 102, forming a plasma 201 b containingelectrons and ions (e.g., protons 201 a) in region 201. The plasmaelectrons may then be driven towards the first section 120 a of the ionbeam transport and irradiation system 120 and the plasma electrons maypull ions with them towards the first section 120 a. The distance fromthe target 200 to the treatment field 150, d2, may also be less thanapproximately 1 m. Therefore, the combination of distances d1 and d2 maybe less than approximately 1 m. The target 200 may be a film or foilthat is rolled into position on rollers 109 under control of controller160 for each shot of the light source system 101. The target 200 mayinclude a target portion and a prepulse controller portion whichcontrols the prepulse of the pulse 102 or reduces it. Both targetportion and prepulse controller portion may be moved synchronously withthe pulse shots from light source 101 to expose a fresh film surface.The target 200 will be discussed in further detail below.

[0026] The first section 120 a of the ion beam transport and irradiationsystem 120 is located inside vacuum chamber 108. The second section 120b of the ion beam transport and irradiation system 120 is locatedbetween the vacuum chamber 108 and the treatment field 150. The firstand second sections 120 a, 120 b of the ion beam transport andirradiation system 120 may include slit 122, magnet or magnets 123, beamdump 130, shields 124, magnet or magnets 125, filter or filters 126,aperture or apertures 127, foil or foils 128, magnet or magnets 129,optional electronic guide 131 and sensors 103. The first and secondsections 120 a, 120 b may include other transportation and controlelements not shown in FIGS. 1A-1C. Second section 120 b may optionallyinclude a support of the treatment field 150 for irradiation of apatient (support is not shown) in oncological applications.

[0027] The ion beam transport and irradiation system 120 is configuredto discriminate among various radiation components produced by the pulse102 striking the target 200. The ion beam transport and irradiationsystem 120 is designed to achieve this discrimination by isolatingpredetermined energy ions which are to be used in irradiating thetreatment field 150 and separating (i.e., dumping) the radiationcomponents which are not to be used in the irradiation on the treatmentfield 150. The radiation components which result from the pulse 102striking the target 200 include different species of ions (e.g.,protons), x-rays, electrons, remnants of the pulse 102, and differentenergy components (e.g., MeV, 10's MeV, and 100's MeV within a certainenergy band or window). After ion generation from the target 200, ionssuch as protons 201 a with a predetermined emittance are allowed to passthrough the slit 122 in the form of an ion beam 102 a. Beyond the slit122, magnets (or magnet) 123 are designed to discriminate the energy ofthe predetermined protons (and other types of radiation) by bending thedifferent species and components of radiation and directing theremaining portion of the ion beam 102 a into beam dump 130. The magnets123 may be pulsed as well as electronically modulated for control aswell as for scanning. Combined with the magnets 123 are shields 124 andfilter or filters 126 which may also be used not only to protectundesired radiation from hitting the treatment field 150 forirradiation, but also to define and discriminate a predetermined portionof the phase space of the given radiation component to be delivered tothe treatment field 150. A beam aperture 127 may be used to control thesize of the beam 102 a to irradiate the treatment field 150. A pluralityof high Z metallic foils 128 may be configured inward to stop low energyor low ranged components of radiation and monitor the ion beam 102 a.Magnet(s) 129 may control the direction of the ion beam 102 a. Anoptional electronic guide 131 may be placed after the magnet(s) 129 toperform a scanning function of the ion beam 102 a on the treatment field150.

[0028] The width, angle and emittance of the ion beam 102 a whichstrikes the treatment field 150 is controlled by a combination ofaccelerator system 100 design choices. These design choices may includethe nature of the target 200 (which will be discussed in detail below),the light source system 101 intensity and focus, the distance of thelight source system 101 from the target 200, the choice of transportelements (e.g., magnets, filters, foils, shields, mirrors, and slits),the width of the beam aperture 127, and the use of an optionalelectronic guide 131. The size of the light source (e.g., laser) spot150 a on the treatment field 150 may vary from about 0.5 to about 20 cm₂in area in accordance with accelerator system 100. For example, apointed, small emittance beam (i.e., a pencil beam producing a lightsource spot 150 a of approximately 0.5 to approximately 2 cm²) on theorder of approximately 1 millimeter milliradians (mm mrad) may beproduced by the accelerator system 100. Such a small pencil beam may beconfigured to scan through the electronic guide 131 and cover a portionof or the whole region of the treatment field 150 by scanning in apredetermined pattern where irradiation is desired. Therefore, inoncological applications, a small tumor (i.e., in the range ofapproximately 5 to 20 cm) may be more accurately targeted for localizedor conformal treatment.

[0029] The optical elements (e.g., mirror series 104), target 200, themagnets 123, 125, and 129 and other transport elements may be controlledadaptively through the controller 160 and feedback system 170 during andafter each shot from light source system 101. Through the use of thecontroller 160 and feedback system 170, the control and modulation ofthe beam energy, energy band, size, and repetition rate may beachieved—shot by shot—of the light source system 101. The ion beamtransport and irradiation system 120 may also be configured todiscriminate a portion or portions of the ion beam 102 a in angle andsize to adjust the beam's size, emittance, and flux for predeterminedion beams 102 a which allows for a highly flexible system.

[0030] At least four parameters of the target 200 may be varied toobtain a change in performance of the ion beam 102 a which strikes thetreatment field 150. These four parameters may include the width,material, geometry (or shape) and surface of the target 200. Themodification of these parameters allows for the maximization of theinteraction of the pulse 102 and the target 200 and the maximization ofthe energy and flux of the ion beam 102 a which results from the pulse102 striking the target 200. A detailed discussion of the fourparameters follows.

[0031] The pulse 102 which strikes the target 200 has a field (e.g.,laser field) with an intensity in the ultra-relativistic region. In theultra-relativistic region, the electron momentum in the field exceedsmc, where m is the electron rest mass and c the speed of light, so thatthe electron energy in the field far exceeds that of electron rest mass(e.g., at least approximately 10²¹ W/cm²). The pulse 102 may beirradiated over a small spot 200 a (as shown in FIG. 2) (e.g.,approximately 2 to approximately 10 square microns) on the target 200.The target 200 acts as an ion source as well as an accelerator, emittingenergetic ions (e.g., protons 201 a as shown in FIGS. 1A-1B) in theplasma region 201 behind the target 200. As discussed above, the plasmaregion 201 is followed in sequence by the ion beam transport andirradiation system 120 which may extract a predetermined band of protons201 a from the plasma region 201. The beam 102 a which emerges from theion beam transport and irradiation system 120 will be an ion (e.g.,proton) beam and is capable of irradiating the treatment field 150 of apatient.

[0032]FIG. 2 illustrates an enlarged side view of the target 200. Thefirst parameter of the target 200 that may be varied is the material ofthe target 200. The target 200 may be a multilayer material having afirst layer 202 and a second layer 204. These layers 202, 204 may be twodifferent materials or bi-material (e.g., bi-metal). The layers 202 and204 may be adhered together. The first layer 202 of the target 200 isdesigned to reflect the low-intensity prepulse of the pulse 102 andbecome transparent at higher intensities of the pulse 102 very quicklyafter being struck. The first layer 202 may be a metal or semiconductingfilm material. The first layer 202 may be made of a higher Z materialthan the second layer 204. For example, first layer 202 may be aluminum,carbon, gold, or lead. A high Z material may contain high atomic numberatoms that generate a large number of electrons, but ions in thissetting do not gain much energy, while most of the pulse energy isabsorbed here. The first layer 202 is capable of converting the photonmomentum of the pulse 102 which strikes the target 200 into electronmomentum. The first layer 202 may also compress the pulse 102 further bya small factor so that the intensity of the pulse increases at themoment of its impingement on the surface of the target 200 by theelectromagnetic (EM) ponderomotive drive of electrons into the interiorof the first layer 202. The second layer 204, on the side of the target200 opposite to the entry of the pulse 102, may be made of proton richlower Z materials (e.g., hydrogen, hydrogen rich materials, plasticsmade of carbon, and water) than the first layer 202 material. Low Zmaterials contain low atomic number atoms that do not generate as manyelectrons, but generate light ions (e.g., protons, carbon, oxygen ions)and cause a strong electrostatic field. This electrostatic field mayconvert electron energy into ion energy. The second layer 204 mayproduce protons through irradiation leading to ionizing the material inthe second layer 204 instantaneously (i.e., a range of about 1 to about5 femtoseconds). Therefore, the first and second layer configuration mayenhance electron production in the high Z material of the first layer202 and stabilize the hot electron production and subsequent ionproduction. Although a first and second layer are illustrated, it is tobe understood that further layers may also be used.

[0033] The second parameter of the target 200 that may be varied is thethickness, t₃, of the target 200. The thickness t₁ of the first layer202 is designed to be large enough to stop substantially all of thepulse 102. However, it may not be designed to be so large as to capturehot electrons generated by the first layer 202. The typical thickness t₁of the first layer 202 is also dependent and inversely proportional tothe Z value of the material and, therefore, the stopping power. Therange of the thickness t₁ may be approximately 50 to approximately 2000nanometers (nm). If the prepulse of the pulse 102 from the particularlight source system 101 varies longer and larger so as to ablate thefirst layer 202, the thickness t₁ may be increased accordingly. Thethickness t₂ of the second layer 204 may be smaller than the first layer202 and in the range of approximately 10 to approximately 2000 nm, and,typically in the range of approximately 10 to approximately 100 nm.Therefore, the combined thickness of the first and second layers to formthe thickness of the target, t₃, may be in the range of approximately 60to approximately 2500 nm.

[0034] The third parameter of the target 200 that may be controlled isthe shape of the target 200. The geometry (or geometries) of the target200 may enhance the electron density and the ability to trap ions behindthese electrons, thereby increasing both α and l. In order to enhancethe accelerating electrostatic field that results from the pulse 102striking the target 200 and the capacity to capture protons, thegeometry of the target 200 may be substantially concave toward theacceleration direction as shown by reference numeral 206 in FIG. 2. Inaddition, this concave configuration allows direct drive of electronsout of the target 200 into the hollow 200 c of the concavity 206 of thetarget 200 by an electric field caused by the light source (e.g., alaser field) as the angle θ between the target surface and the pulseincident direction allows greater energy and population of electronsdriven out of the target 200. Furthermore, the concave geometryintroduces the ability to control the ion beam optics, such as thefocusability, emittance and enhanced density of the ion beam 102 a. Inalternative embodiments, a plurality of concavities may be used insteadof a single concavity.

[0035] As discussed above, reference numeral H indicates the spot sizeof the pulse 102 as it reaches the target 200. The first or light sourceside diameter J of the concavity facing the pulse 102 may be madesubstantially equal to the spot size H and the second or non-lightsource side diameter Y of the concavity 206 may be less than the spotsize H. H, J and Y may each have a radius in the range of approximately1 to approximately 10 microns. In alternative embodiments, H, J and Ymay be designed to be substantially different in dimensions. Forexample, J may be substantially less than H or H may be substantiallyless than J. The concave shape of the target 200 may determine thefocusability of ions (e.g., protons) depending on the curvature of theconcavity 206. Varying the aspect ratio of the concavity 206, or theratio of the diameter Y to the concavity measurement of concavity 206(i.e., the slant of walls 200 d and 200 e off axis A-A), may change thefocal length of the target 200. The smaller the aspect ratio, theshorter the ion focal length. The ion beam 102 a emittance may bedetermined by the spot size H on the target 200 times the angulardivergence of the ion (e.g., proton). The angle, θ, of the concavitymeasurement of concavity 206 (i.e., the slant of walls 200 d and 200 eoff axis A-A), may be in the range of approximately 10 to approximately90 degrees and, typically, may be approximately 40 to approximately 50degrees. The angle, θ, of the concavity measurement of concavity 206with respect to the first and second layers 202, 204 (and the planeparallel to the phase front of the incident pulse 102) may cause thetransverse electric field of the pulse 102 to directly drive electronsinto the first layer 202 and thereby enhance the energy of electronscoming off this first layer 202 to be higher. The nature of theconcavity 206 may hold these electrons from dispersing to sustain a highdensity that sets up a high accelerating electrostatic field in theregion 201. The concave geometry of target 200 allows the charge of theelectron cloud accelerated off the first layer 202 to see image chargenot only behind the charge, but also beside it.

[0036] FIGS. 3A-3E illustrate a series of alternative designs for theconcavity 206 of target 200. FIG. 3A illustrates a concavity 206 with adome shape having a base wider than a narrower curved shape at thedistal end 302. FIG. 3B illustrates a concavity 206 with a substantiallypointed distal end 304. FIG. 3C illustrates a concavity 206 having anenhancement of the concave feature by increasing the angle of theconcavity wall and, therefore, having a substantially circular shape306. FIG. 3D illustrates a concavity 206 with a polygonal shape 308 withwalls being extremely angled. FIG. 3E illustrates a concavity 206 with abase being narrower than a substantially curved shape at the distal end310. These different concavity configurations allow electrons topropagate forward less impeded by the electrostatic force set up betweenthe electrons and ions (which, otherwise, might turn the electrons backbefore the ions get accelerated), while ions are allowed to gainmomentum to reduce the impedance mismatching between electrons and ions.The concave nature of the target 200 also allows the electrostaticfields and magnetic fields which are formed to pinch the electronstoward the axis (A-A in FIG. 2) of the concavity 206, thereby increasingtheir density, which can induce axial electric current and the inducedazimuthal magnetic fields further. These magnetic fields may furtherpinch the electron stream and increase the electron density andaccelerating fields.

[0037] The fourth parameter that may be controlled of the target 200 isthe design of the surface 202 b (as shown in FIG. 2). The targetmaterial surface preparation may be designed so that pulse absorption ismore efficient and resultant electron energy is greater. In order toenhance the absorption of the pulse 102 and the production of energeticelectrons that drive the accelerating field of protons, the surface 202b of the first layer 202 may be roughened. In another embodiment thesurface 202 b of the first layer 202 may have at least one groove whichhas a depth and width of less than approximately 1 micrometer, and,typically in the range of approximately 10 to approximately 100 nm. FIG.4A illustrates a surface 202 b of the target 200 having a plurality ofgrooves 402. FIG. 4B illustrates a surface 202 b having fibers (e.g.,thin fibers) 404. FIG. 4C illustrates a surface 202 b having clusters406 of approximately 10 to approximately 100 nm in diameter. Clustersfrom originally gaseous material may be made by spraying a gas jet intoa vacuum. Another method of creating clusters may be found in U.S. Pat.No. 5,585,020, issued Dec. 17, 1996 to Becker et al. and herebyincorporated by reference. The packing ratio of the clusters may bedefined as the ratio of the space occupied by clusters and thatunoccupied by clusters. The packing ratio of the clusters may be high,specifically, up to about 1:1. A method of forming these clusters mayinclude spraying or adsorbing them onto the second layer 204 of target200 on the side facing the pulse 102. FIG. 4D illustrates a surface 202b composed of foams 408 of approximately 10 to approximately 100 nm indiameter. FIG. 4E illustrates a combination rounded concavity withgrooves 410. The surface preparations illustrated in FIGS. 4A-4E areconducive of enhanced absorption of pulse 102 over a short distancewhich may be approximately less than 1 micron. For example, clusters 406may be capable of absorbing nearly all (i.e., greater than approximately70%) of the pulse energy when the pulse 102 has enough intensity. Thesize of grooves 402, fibers 404, clusters 406 or foams 408 may bedesigned to be shorter than the size of electron excursion in the pulsefield (less than approximately 1 micron). For example, in the case ofcarbon such material may be soot. In alternative embodiments, hydrogenatoms may be adsorbed onto the back surface 204 a (the surface oppositeto the direction of the laser pulse 102 as shown in FIG. 2) of thetarget 200. In order to further control the prepulse of pulse 102,several methods may be used. As discussed above, in front of the target,in reference numeral 107 (as illustrated by FIG. 1B) there may be placedan additional thin foil that is thick enough to absorb most of theprepulse energy of the pulse 102 but thin enough to be burned by thetime the main peak of the pulse 102 arrives.

[0038] The material, thickness, geometry and surface design of thetarget 200 may be predetermined depending on the specific light sourcesystem 101 (e.g., laser system) used as well as the feedback system 170in a shot-by-shot basis. In an alternative embodiment as illustrated byFIG. 5, a prepulse control foil CF may be placed at an angle withrespect to the target 200 surface so as to cut off the prepulse of pulse102 but to transmit the peak main pulse. Most of the prepulse will bereflected as shown by reflected pulse 102 b. In another embodiment, aplasma mirror (a mirror made up of a plasma that may be ionized by thelight source itself or prefabricated) may be employed before the target200 that transmits (or reflects) laser light according to its opticalproperty as a function of intensity. In another embodiment, a frequencymultiplier (i.e., double or triple) may be placed before the target 200using a nonlinear crystal so that weaker prepulse components may be cutoff (i.e., chopped). In another alternative embodiment, a geneticalgorithm (or similar computer software) located in light source system101 or controller 160 may be used to rearrange the spectrum of the broadband light source system 101 to sharpen the front side of the pulse 102.

[0039] When a laser system is used for the light source 101, the laserenergy per laser shot from the laser system 101 is typicallyapproximately 1 to approximately 10 J at the target 200, while theobtainable ion energy from the accelerator system 100 may beapproximately 10 to approximately 100 mJ at a predetermined energy ofapproximately 10 to approximately 500 MeV and typically a predeterminedenergy in the range of approximately 100 to approximately 200 MeV. For aradiation oncology application, a radiation dose of ions (e.g., protons)of approximately 1 to approximately 10 Gray (Gy) on a 1 centimeter (cm)²area over the 10 cm range of 100 MeV portons, may yield 10 cm³ volume ofirradiated tissue. (The range may also depend on factors such as the ionfocus size). Therefore, the accelerator system 100 may be capable ofproducing an ion beam 102 a which may penetrate approximately 10 toapproximately 20 cm beneath the surface of skin tissue in the treatmentfield 150 of a patient to reach a tumor sight; produce a dose per shotat the treatment field 150 in the range of approximately 0.1 toapproximately 10 Gy; and produce a dose per second at the treatmentfield of approximately 0.1 to approximately 100 Gy/second. If the lightsource system 101 repetition rate is approximately 10 Hz, a dosedelivered to the treatment field 150 by the accelerator system 100 inless than approximately 1 second may be capable of treating a smalltumor target on the order of approximately 1 square cm or less. If thetumor target is larger than approximately 1 square cm, a dose deliveredby the accelerator system 100 may be capable of treating the tumortarget in less than approximately 1 minute.

[0040]FIG. 6 discloses an alternative accelerating system and method500. Housing 501 may be a needle or a syringe. Housing 501 may have alength, d6, of approximately 10 to approximately 40 cm and width, d5, ofapproximately 50 to approximately 300 microns. Contained within thehousing 501 are a first section 502 connected to a second section 504.The first section 502 may be a fiberglass or fiberoptic material and isconnected to a light source system (e.g., a laser system) 506 which iscapable of producing an energy pulse 510 (e.g., laser pulse). The firstsection 502 may vary in length depending on the application. Typically,the first section 502 may vary from about 0.1 to 10 meters. A protectivesurrounding such as housing 501 may be used so that any stray light maybe reflected and/or absorbed in case the application of the light sourcesystem 506 is to human tissue. The first section 502 and second section504 are used as a light source guide to a target 508. Target 508 may berolled into laser shot position (as shown in FIG. 6) through a deliverysystem such as rollers 530. Typically, the target 508 may be placed in apredetermined position before each shot of the light source system 506.The second section 504 may also be a hollow fiberglass (or fiberoptic)material. The second section 504 may be capable of conducting pulses 510(e.g., short pulses) with intensity exceeding approximately 10¹⁶ W/cm²over a distance of approximately 10 cm. The pulse 510 is propagatedthrough the first section 502 and second section 504 to a spot inproximity to the target 508. The length of the first section 502 is mayvary depending on the specific application. Light source system 506 maybe a chirped-pulse amplification (CPA) based compact high-repetition,high fluence laser system (e.g., a Ti: sapphire laser). The light sourcesystem 506 may be inversely chirped so that as the pulse 510 propagatesthrough the first section 502 and the second section 504 the pulse 510may contact itself in time domain to yield maximally allowed intensity(e.g., approximately 10¹⁷ W/cm²). Specifically, the pulse 510 (which wasoriginally time stretched) may, in the first half of the CPA technique,be compressed by a compressor (not shown) only to the extent that thepulse 510 does not exceed a threshold intensity (approximately 10¹⁶W/cm² or less), which may be further compressed through the secondsection 504. The second section 504 may be constructed such that itsfiber radius, length, and index of refraction may be designed so thatafter the pulse 510 exits the second section 504, the maximum timecompression of the pulse 510 may be achieved. The mode of the pulseelectromagnetic wave should be that of J₀ (i.e., the zeroth order Besselmode [F.Dorchies et al., Phys.Rev. Lett. vol. 82, p.4655(1999)]) toavoid surface damage on the fiber of second section 504. The pulselength at the target 508 irradiation is designed to maximally excite theshock wave resulting from the pulse striking the target 508. The tip 504a of the second section 504 may be replaceable if necessary after thematerial damage caused by the pulse 510 and/or radiation.

[0041] The diameter d7 of the second section 504 may be approximately 30to approximately 500 microns, and typically, approximately 75 toapproximately 125 microns. The resulting laser spot LS on the target 508also has a size d8 of approximately 100 microns. The accelerated numberof protons is approximately 10¹¹ per laser shot with typical protonenergies of approximately 1 MeV. The resulting ion (e.g., proton) beam510 a is directly irradiated on the treatment field 510 (e.g.,biological issues) from a distance d4 which may in the range ofapproximately 0.1 to approximately 10 millimeters. After the treatmentfield 510, a backscatter film (e.g., higher Z metal such as aluminum(Al)) 540 may be positioned with a thickness of approximately 10 toapproximately 50 microns to absorb radiation. Backscatter film 540serves to backscatter x-rays toward the treatment field 510. Therefore,the geometry of the backscatter film 540 may be straight as shown inFIG. 6 or concave or another shape that surrounds the treatment field510.

[0042] Target 508 may be constructed in several ways. The target 508 maybe constructed by varying at least four design parameters (thickness,material geometry, and surface) similarly to the target 200 as discussedabove with respect to FIGS. 1-4E. In another embodiment, target 508 maybe a thick, dense film such as plastic or a metal coated plastic. Inanother embodiment, target 508 may have a coating of metallic vaporsurface designed to face the direction of the pulse 510. In anotherembodiment, target 508 may be a metallic foil coated with hydrogengas/liquid (e.g., water) spray 602 on the side facing away from thelaser pulse 510. In another embodiment, target 508 may be a spongymaterial with a porous structure (e.g., hydrocarbon, ceramic, or metalscapable of absorbing a large amount of hydrogen or hydrogen richsubstance) immersed in hydrogen. In another embodiment, shown in FIG. 7,a foil 704 made of a metallic material (e.g., Al) having a thickness inthe range of approximately 10 to approximately 30 microns may be placedspaced apart from target 508 to screen the treatment field 510 fromradiations of different characters and energies.

[0043] The accelerator system 500 may be used in the case of a medicalapplication such as radiation oncology which allows for the irradiationof a treatment field such as tumorous tissue in situ (or under the skinsurface) rather than from the exterior of the patient's body. Inaccelerating system 500, ions (e.g., protons) are delivered to the spotof the tumor, for example, through a bodily opening or incision.Therefore, the typical energy of 100 to 200 MeV for a 10 to 20 cm rangeis not required. This type of irradiation is therefore nearly directwithout significantly affecting healthy tissues.

[0044] The embodiments disclosed in FIGS. 1-5 illustrate a system andmethod that may enable the delivery of ions (e.g., protons) energeticenough to make sufficiently high radiation dose for oncology and otherapplications. The disclosed embodiments may operate compactly, flexiblyand inexpensively. The disclosed embodiments may be based on a highpower compact light source irradiating a target(s) and associateddevices described above. Many radiation oncology applications requireirradiation of protons from outside of a body. Therefore, theseapplications may require energies beyond 100 MeV with a dose ofapproximately 1 Gy. The disclosed embodiments feature a method that maygo beyond approximately 100 MeV with sufficient dose and irradiationproperties needed for radiation oncology applications. Elements of thedisclosed embodiments (which are described above) may include:deployment of intense compact high repetition laser and its conditions(particular laser technology to be deployed, intensity, pulse duration,aperture, and pulse shaping), irradiation of a target whose thickness,material (bimetal or bi-metal), geometry (concave and other variations)and surface (clusters or frustrated surface or other variations) arespecified, the focusability and transport of the ion beams by the targetgeometry and additional magnetic and other transport devices, theprepulse control measures, the flexible adjustment, monitor, andfeedback of various parameters of laser, target, optics, transportsystem, and treatment field, the overall systems concept, which amongother things, allow flexible, compact, and inexpensive deployment ofthis device that includes intra-operative and portable usage as well aspotential compatibility with existing treatment facilities. UnlikeX-rays and electron beams, ion (e.g., proton) beams have a sharp Braggpeak, enabling the deposition of the precise dose at a predeterminedlocation. With these flexible capabilities enabled in the disclosedembodiments a precise and flexible deposition of radiation dose may bepossible. The disclosed embodiments may give rise to energies of beamprotons (and other ions) in excess of approximately 100 MeV and doses inthe range of approximately 0.01 to approximately 100 Gy, (and typicallyapproximately 1 Gy), over an approximately 0.1 to approximately 100second period (and typically approximately one second), which are in therange of oncological needs.

[0045] The embodiments disclosed in FIGS. 6-7 allow for a compactdelivery of protons, whose energy may be in the range of sub-MeV toseveral MeV with a similar (or less) dose. Since these embodiments maybe inserted substantially adjacent to the location of the treatmentfield, this energy is sufficient to treat oncological targets.

[0046] The foregoing is for illustrative purposes and is not to beconstrued as limiting thereof. The invention is defined by the followingclaims, with equivalents of the claims to be included therein.

The invention claimed is
 1. A target comprising: a film having aconcavity.
 2. A target comprising: a first layer and a second layer. 3.The target of claim 2, said first layer having a thickness in the rangeof approximately 50 to approximately 2000 nm; and said second layerhaving a thickness in the range of approximately 10 to approximately 500nm.
 4. The target of claim 2, said first layer having a substantiallyconcave shape.
 5. The target of claim 2, said first layer having aconcavity with a substantially pointed distal end.
 6. The target ofclaim 2, said first layer having a substantially cylindrical shapedconcavity.
 7. The target of claim 2, said first layer having asubstantially polygonal shaped concavity.
 8. The target of claim 2, saidfirst layer having a concavity; and said concavity having a base and asubstantially curved shape at a distal end of the concavity.
 9. Thetarget of claim 2, said first layer having a concavity; and saidconcavity having a base and a substantially curved shape at the distalend of the concavity.
 10. The target of claim 2, wherein said firstlayer is a high Z metal.
 11. The target of claim 10, wherein said secondlayer is a lower Z material than said first layer.
 12. The target ofclaim 2, wherein said first layer is selected from the group consistingof aluminum, carbon, gold and lead.
 13. The target of claim 2, whereinsaid second layer is from the group consisting of plastic and water. 14.The target of claim 2, wherein said first layer has a surface with atleast one groove.
 15. The target of claim 2, wherein said first layerhas a plurality of grooves.
 16. The target of claim 15, wherein said atleast one groove has a depth in the range of approximately 10 toapproximately 100 nm.
 17. The target of claim 2, wherein said firstlayer has at least one groove having a width in the range ofapproximately 10 to approximately 100 nm.
 18. The target of claim 2,wherein said first layer is composed of a plurality of fibers.
 19. Thetarget of claim 2, wherein said first layer is composed of a pluralityof clusters.
 20. The target of claim 19, wherein each of said pluralityof clusters are approximately 10 to approximately 100 nm in diameter.21. The target of claim 2, wherein said first layer is composed of aplurality of foams.
 22. The target of claim 21, wherein said pluralityof foams are approximately 10 to approximately 100 nm in diameter. 23.The target of claim 2, wherein hydrogen is adsorbed into the secondlayer on the side opposite of the first layer.
 24. The target of claim2, wherein first layer is capable of absorbing greater thanapproximately 70% of the energy of an energy pulse.
 25. An acceleratorsystem comprising: a light source; and a target having a thickness inthe range of approximately 60 to approximately 2500 nm.
 26. Anaccelerator system comprising: a light source; a target having a firstlayer with a thickness in the range of approximately 50 to approximately2000 nm; and said target having a second layer with a thickness in therange of approximately 10 to approximately 500 nm.
 27. An acceleratorsystem comprising: a light source; and a target having a substantiallyconcave shape.
 28. An accelerator system comprising: a light source; anda target having a shape selected from the group consisting of aplurality of concavities, a concavity with a substantially pointeddistal end, a cylindrical shaped concavity, a polygonal shapedconcavity, and a concavity with a base and a substantially curved shapeat the distal end of the concavity.
 29. An accelerator systemcomprising: a light source; and a target having a first layer formedfrom a high Z material and a second layer formed from a material havinga lower Z than the high Z material.
 30. The accelerator system of claim29, wherein said high Z material are selected from the group consistingof aluminum, carbon, gold and lead.
 31. The accelerator system of claim29, wherein said lower Z material in the second layer is selected fromthe group consisting of plastic and water.
 32. An accelerator systemcomprising: a light source; and a target having at least one groove. 33.The accelerator system of claim 32, wherein said at least one groove hasa depth of less than approximately one micrometer.
 34. The acceleratorsystem of claim 32, wherein said at least one groove has a depth in therange of approximately 10 to approximately 100 nm.
 35. An acceleratorsystem comprising: a light source; and a target having a surfaceselected from the group consisting of a plurality of grooves, aplurality of thin fibers, a plurality of foams and a plurality ofclusters.
 36. An accelerator system comprising: a light source; and atarget having a plurality of clusters.
 37. An accelerator systemcomprising: a light source; and a target having a plurality of foams.38. An accelerator system comprising: a light source; and a targethaving hydrogen adsorbed into the side opposite of the position of thelight source.
 39. An accelerator system comprising: a light sourcecapable of producing an energy pulse; a target having a first layer anda second layer; and wherein said first layer is capable of absorbinggreater than approximately 70% of the energy of said energy pulse. 40.An accelerator comprising: a laser system; a target having a first layerand a second layer arranged to receive a laser pulse from said lasersystem; and a beam transport system operatively coupled to said targetand having an electronic guide.
 41. The accelerator system of claim 40,wherein said beam transport system is comprised of elements selectedfrom the group consisting of slits, filters, magnets, foils and shields.42. The accelerator system of claim 40, wherein the target isoperatively connected to at least one roller.
 43. An accelerator systemcomprising: a light source capable of producing an energy pulse; atarget having a first layer and a second layer; said first layer havinga thickness in the range of approximately 50 to approximately 2000 nm;said second layer having a thickness in the range of approximately 10 toapproximately 500 nm; and said first layer having a substantiallyconcave shape.
 44. A system comprising: a light source capable ofproducing an energy pulse; a target having a first layer and a secondlayer; said first and second layers having a combined thickness in therange of approximately 60 to approximately 2500 nm; said first layerhaving a substantially concave shape; said first layer having a groovedsurface; wherein said first layer is a high Z metal material and saidsecond layer is a lower Z metal material; and wherein said first layeris capable of absorbing greater than approximately 70% the energy ofsaid energy pulse.
 45. A system comprising: a light source capable ofproducing an energy pulse; a target having a first layer and a secondlayer; and wherein said first layer is capable of absorbing greater thanapproximately 70% of the energy of said energy pulse.
 46. A systemcomprising: a light source capable of producing an energy per laser shotof between approximately 1 and approximately 10 Joules; and a transportsystem capable of delivering energy in the range of approximately 10 toapproximately 500 MeV.
 47. A system comprising: a light source capableof producing an energy per laser shot of between approximately 1 andapproximately 10 Joules; and a transport system capable of deliveringenergy in the range of approximately 100 to approximately 200 MeV. 48.An accelerator system comprising: a light source capable of producing anenergy per laser shot of between approximately 1 and 10 approximatelyJoules; a target positioned to receive a laser shot from said lightsource; and a transport system capable of delivering energy in the rangeof approximately 10 to approximately 500 MeV.
 49. The accelerator systemof claim 48, wherein said target has a first layer and a second layer;and said first and second layers having a combined thickness in therange of approximately 60 to approximately 2500 nm.
 50. The acceleratorsystem of claim 48, wherein said target has a substantially concaveshape.
 51. A system comprising: a light source capable of producing anenergy per laser shot of between approximately 1 and approximately 10Joules; and a means for delivering energy in the range of approximately10 to approximately 500 MeV to a treatment field.
 52. A systemcomprising: a light source capable of producing an energy pulse; and ameans for delivering energy in the range of approximately 10 toapproximately 500 MeV to a treatment field.
 53. A system comprising: alight source capable of producing an energy pulse; a means for absorbinggreater than approximately 70% of the energy of said energy pulse andproducing radiation elements; and a means for discriminating saidradiation elements to deliver energy in the range of approximately 10 toapproximately 500 MeV to a treatment field.
 54. A method comprising:firing a pulse having an energy range of approximately 1 toapproximately 10 Joules from a light source at a target; guidingradiation elements emitted from said target; discriminating ions havinga predetermined energy range from said radiation elements; anddelivering said ions in an energy range of approximately 10 toapproximately 500 MeV to a treatment field.
 55. A method comprising:firing a pulse having an energy range of approximately 1 toapproximately 10 Joules from a light source at a target; guidingradiation elements emitted from said target; discriminating ions havinga predetermined energy range from said radiation elements; anddelivering said ions in an energy range of approximately 100 toapproximately 200 MeV to a treatment field.
 56. A method of delivering aradiation dose to treat an oncological treatment field comprising:firing a pulse having an energy range of approximately 1 toapproximately 10 Joules from a light source at a target; guidingradiation elements emitted from said target; discriminating ions havinga predetermined energy range from said radiation elements; anddelivering said ions in an energy range of approximately 100 toapproximately 200 MeV to said oncological treatment field.
 57. A methodcomprising: firing a pulse from a light source at a target having asubstantially concave shape; guiding radiation elements emitted fromsaid target; discriminating ions having a predetermined energy rangefrom said radiation elements; and delivering said ions in an energyrange of approximately 10 to approximately 500 MeV to a treatment field.58. A method comprising: firing a pulse from a light source at a targethaving a substantially concave shape; guiding radiation elements emittedfrom said target; discriminating ions having a predetermined energyrange from said radiation elements; and delivering said ions in the formof a beam having a spot size of approximately 0.5 to approximately 20cm² on a treatment field.
 59. A method comprising: firing a pulse from alight source at a target having a roughened surface; guiding radiationelements emitted from said target; discriminating ions having apredetermined energy range from said radiation elements; and deliveringsaid ions in an energy range of approximately 10 to 500 MeV to atreatment field.
 60. A method comprising: firing a pulse from a lightsource at a target having a first layer made from a high Z material anda second layer made from a lower Z material; guiding radiation elementsemitted from said laser pulse striking said target; discriminating ionshaving a predetermined energy range from said radiation elements; anddelivering said ions in an energy range of approximately 10 toapproximately 500 MeV to a treatment field.
 61. A method comprising:firing a pulse from a light source at a target having a shaped surface;guiding radiation elements emitted from said target; discriminating ionshaving a predetermined energy range from said radiation elements; anddelivering said ions which may penetrate about 10 to about 20 cm beneaththe surface of skin tissue in a treatment field.
 62. A methodcomprising: firing a pulse from a light source at a target having ashaped surface; guiding radiation elements emitted from said target;discriminating ions having a predetermined energy range from saidradiation elements; and delivering said ions to produce a dose per shotat a treatment field in the range of about 0.1 to about 10 Gy.
 63. Amethod comprising: firing a pulse from a light source at a target havinga shaped surface; guiding radiation elements emitted from said target;discriminating ions having a predetermined energy range from saidradiation elements; and producing a dose per second at a treatment fieldof approximately 0.1 to approximately 100 Gy/second.
 64. A methodcomprising: adhering a first layer material to a second layer ofmaterial; and forming said first and second layers into a substantiallyconcave shape.
 65. A method comprising: adhering a first layer of high Zmaterial to a second layer of lower Z material; and forming said firstand second layers into a substantially concave shape.
 66. A systemcomprising: a light source capable of producing an energy per laser shotof between approximately 1 and approximately 10 Joules; a target capableof producing radiation elements; and a transport system capable ofdelivering energy which may penetrate about 10 to about 20 cm beneaththe surface of skin tissue in a treatment field.
 67. A systemcomprising: a light source capable of producing an energy per shot ofthe light source of between approximately 1 and approximately 10 Joules;a target capable of producing radiation elements; and a transport systemcapable of delivering energy to produce a dose per shot at a treatmentfield in the range of about 0.1 to about 10 Gy.
 68. A system comprising:a light source capable of producing an energy per shot of the lightsource of between approximately 1 and approximately 10 Joules; a targetcapable of producing radiation elements; and a transport system capableof delivering energy producing a dose per second at a treatment field ofapproximately 0.1 to approximately 100 Gy/second.
 69. A systemcomprising: a light source; a fiber optic section operatively coupled tosaid light source; and a target having a concavity.
 70. The system ofclaim 69, further comprising: a housing surrounding said target.
 71. Thesystem of claim 69, further comprising: a housing surrounding said fiberoptic section.
 72. The system of claim 69, further comprising: a housingsurrounding said target and said fiber optic section.
 73. The system ofclaim 70, wherein said housing is a needle.
 74. The system of claim 70,wherein said housing is a syringe.
 75. The system of claim 70, whereinsaid housing has a diameter of approximately 50 to approximately 300microns.
 76. The system of claim 70, wherein said housing has a lengthof approximately 10 to approximately 40 cm.
 77. The system of claim 69,wherein said fiber optic section has a thickness in the range ofapproximately 30 to approximately 500 microns.
 78. The system of claim69, wherein said target has first layer having a thickness in the rangeof about 50 to about 2000 nm and a second layer having a thickness inthe range of about 10 to about 500 nm.
 79. The system of claim 69,wherein the target having a surface selected from the group consistingof a plurality of grooves, a plurality of thin fibers, a plurality offoams and a plurality of clusters.
 80. The system of claim 69, whereinthe target having a first layer formed from a high Z material and asecond layer formed from a material having a lower Z than the high Zmaterial.
 81. The system of claim 80, wherein said high Z material isselected from the group consisting of aluminum, carbon, gold and lead.82. The system of claim 80, wherein said lower Z material in the secondlayer is selected from the group consisting of plastic and water. 83.The system of claim 69, wherein said target having a shape selected fromthe group consisting of a plurality of concavities, a concavity with asubstantially pointed distal end, a cylindrical shaped concavity, apolygonal shaped concavity, a concavity with a base and a curved shapeat the distal end of the concavity, and a concavity having a base and acurved shape at the distal end of the concavity.
 84. The system of claim69, wherein said fiber optic section is capable of being located withina range of approximately 0.1 to approximately 10 millimeters from atreatment field.
 85. The system of claim 69, wherein said target may befrom the group consisting of plastic, metal coated plastic, metallicfoil coated with hydrogen gas/liquid spray, and a spongy materialimmersed in hydrogen.
 86. A system comprising: a light source; a firstfiber optic section operatively coupled to said light source; a secondfiber optic section operatively coupled to said first fiber opticsection; and a target having a concavity.
 87. A system comprising: ameans for emitting an energy pulse; a means for guiding said energypulse to a target; and the target having a concavity.
 88. A methodcomprising: firing a pulse from a light source; guiding said pulsethrough a fiber optic section to a target; and delivering radiationelements emitted from said target to a treatment field.
 89. A method ofdelivering a radiation dose to treat an oncological treatment field in apatient comprising: firing a pulse from a laser; guiding said pulsethrough a fiber optic section to a target; and delivering radiationelements emitted from said target to the oncological treatment field inthe patient.
 90. The method of claim 89, further comprising: positioningsaid fiber optic section beneath the skin surface of the patient.